Fast & Slow Pointers LeetCode 141

Linked List Cycle / visualized

Detect whether a linked list loops back on itself. Slow 🐢 takes one step, fast 🐇 takes two. If there's a cycle they're guaranteed to meet inside it; if not, fast runs off the end. Set the values and where the tail links back.

Node values (comma-separated)

Tail connects to

Execution

idle

Press Run to begin.

0 / 0

Speed

Java · running line

slow 🐢 fast 🐇 meeting point null / end

O(n) time · O(1) space · the gap between the pointers shrinks by one node each loop, so inside a cycle a collision is inevitable.